Ribbon brake unit with inertia control



Nov. 20, 1956 DOQLITTLE 2,771,128

RIBBON BRAKE UNIT WITH INERTIA CONTROL Original Filed Jan. 31, 1950 INVENTOR 25 Donald B. Dooltfii'le.

ATTORNEY Unitfid States Patent RIBBON BRAIQE UNIT WITH INERTIA CONTROL Donald B. Doolittle, Wilmington, Del., assignor, by mesne assignments, to All American Engineering Company, Wilmington, Del., a corporation of Delaware Continuation of application Serial No. 141,563, January 31, 1950. This application August 15, 1952, Serial No. 304,483

4 Claims. (Cl. 155-189) The present invention relates to shock absorbing means for use in connection with aircraft seats and body harness for the protection of passengers during crash landings and the like, and is a continuation of my prior co-pending application, Serial No. 141,563, filed January 31, 1950, now abandoned, for the same general subject matter.

Heretofore there have been numerous arrangements of the body harness and various arrangements for connecting the same to the passenger seats or chairs of an airplane. Such harness and chair connections should be made so as to normally stretch for a limited extent thus providing for the comfort and freedom of the passenger during normal conditions.

These harness and chair connections in the event of a crash develop a shock or stress measurable in units of gravity and safety harness, belts, and the like should be designed to absorb the shock of a crash landing exceeding the threshold of a maximum tolerable acceleration sufficiently to prevent serious injury to the passenger and prevent an excess of the maximum tolerable acceleration from being imparted to a chair occupant.

The principal object of the present invention is to provide a novel shock absorbing arrangement for safety harness used in connection with aircraft passenger chairs adapted to maintain forward acceleration forces imparted to the harness wearer and chair occupant resulting from crash acceleration forces of the craft below a maximum tolerable acceleration threshold.

Another object is to provide a seat belt and/ or harness brake adapted to be operated automatically by an accelerometer or the like in the event of crash in response to forward acceleration forces of a vehicle which develop units of gravity beyond a known standard maximum tolerable G, said brake being arranged to restrain the forward forces imparted to a wearer of the belt below the maximum threshold of tolerable G.

vA further object is to provide means in combination with an elongated flexible member connected to the shoulder straps and waist portions of a safety harness for an occupant of an aircraft seat, brake shoes mounted on each side of the member and an accelerometer adapted to serve to initially actuate means to develop a source of energy responsive to forward acting acceleration forces bracket 14 and the base of a numerals and are referred to by the same numerals in the specification:

Figure 1 is a side elevational view of the present invention applied to a safety harness and seat in which an occupant is seated.

Figure 2 is a side view partly in cross section of the main shock absorber unit of the present invention for the harness shoulder straps. 4

Figure 3 is a longitudinal cross section view of the auxiliary unit for the waist strap or belt of the harness.

Referring in detail to the drawings and first with particular reference to Fig. 1, the floor of an aircraft or any other mobile object is indicated by A. Mounted on the floor A is the base B of a chair or seat S. For the purpose of clearly illustrating the present invention the figure of a man is shown seated in a chair with a form of safety harness H arranged about his body and connected as will be hereinafter described to the novel shock absorbing means of this invention.

'The body harness may be of any form desired but it is preferably made with well known quick detachable connections including a hook with a sliding retainer, such as 10, 10a and 11, 11a, respectively formed on the free ends of the safety harness shoulder and waist straps 12 and 13, respectively. Extending from the rear of the seat A is a bracket 14 for the main bracket is preferably positioned above the base B of the seat and formed with a flange 15 in which are formed openings to receive fastening means such as the bolts 16.

These bolts 16 secure to the flanged head end of the cylinder 17. The cylinder 17 is specially formed so as to have a relatively large lower portion housing a piston 17a. The cylinder 17 opens at the top into a smaller cylinder 18 which serves as a cartridge chamber. The base portion of the cylinde-r17 is formed at diametrically opposite points with transverse slots 19 and 20. Extending through and across the bore of the cylinder and passing through the said slots is an elongated flexible member 21. This member 21 is preferably in the form of a metal tape or ribbon and is made of a thickness suflicient to permit the same to be longitudinally tapered as shown in Figs. 2 and 3. The ribbon 21 as it extends through the cylinder 17 is engaged on each side by a pair of upper and lower brake shoes 22 and 23, respectively.

One end of the ribbon 21 is connected by the quick detachable means 1010a to the free end of the shoulder harness strap 12 and the opposite end of the tape 21 is connected to a coil spring 24 by means of a similar quick detachable connection 25. The opposite end of the spring 24 in turn is secured to a bolt 26 on a bracket 7 -27 anchored to the floor A of the aircraft.

' absorbing ribbon 21 will give against the tension of the for actuating the brake shoes to restrain the resulting forward movement of the wearer of the harness and occupant of a seat below the threshold of a predetermined maxi-- mum tolerable G, whereby the forward movement of the seat occupant is retarded so as not to exceed a tolerable G by the frictional resistance of the brake shoes to the travel of the flexible member therebetween.

With the above and other objects in view, the present invention consists of the novel construction, arrangement and combination of parts, wherein, for example, one embodiment of the same is hereinafter described and illustrated in conjunction with the accompanying drawings.

In the-drawings wherein like parts are given the same" spring 24. This is possible due to the fact that the brake shoes 22 and 23 on each side of the ribbon are inoperative except when actuated by accelerations of the carrying vehicle developed in a crash.

The cartridge chamber 18 is formed with lugs 28 around the lower part of its internal bore at the juncture connecting with the top of the cylinder 17. These lugs support a cartridge 29, which may be of the explosive variety or merely a C02 gas cartridge. The top wall 30 of the cartridge chamber 18 is formed with a centrally located opening in which is mounted a firing pin 31 adapted to be projected forwardly by a weight 32 into the cartridge 29. I

The weight 32 is normally caged in an accelerometer housing 33 mounted at the rear of the cartridge chamber *18. The bottom of the housing 33 is formed with a central shock absorber. This.

opening through which extends the upper end of the firing pin- 31 permitting it to be struck by the weight 32. This weight is caged or held suspended toward the top of the housing 33 above the firing pin by an arm 34 mounted atits forward end'on a pivot pin 35. The pin 35 extends transverse bifurcated cars 36 on the top wall of housing 33;

The arm 34 is formed on its underside with an intermediate lug 37 to the left of the pivot pin 35. This lug 37 engages the firing weight 32 and holds the same in caged position with the assistance of a coiled tension spring 40 connected at one end of the free end of the arm 34 through an eyelet connection 39; and at the other end-to the head of a bolt fastener 41 threadedly secured in the wall of the housing 33. Extending upward from. the top side of the arm 34 opposite the lug 37 is a second arm with an enlarged weighted end 38. The tension of the'spring 40 is calibrated against the weight 38 so as to normally hold the weight 32 caged from the firing pin 31. Such caged condition is calculated to remain unreleased during normal conditions, but in the event of a crash forward acceleration forces developed therefrom as low as 1 or 2 units of gravity causes the weight 38 to shift forwardand arm 34 to be pivoted upward stretching the tension-spring 4t and releasing the lug 37 from the weight 32. The weight 32 is moved forward onto the head of the firing pin 31 by the forward acceleration forces, thereby firing'the cartridge 29.

When the cartridge is fired the resulting gases expand within the cylinder 17 back of the piston 170: thus applying the brake shoes to the flexible member or ribbon 21. Such application of the brake shoes restrains the occupant of the seat from moving forward in excess of a known or tested standard of a maximum tolerable acceleration threshold, which may be as high as from 20 to 30 units of gravity. The standard maximum acceleration is the maximum units of gravity which the human body can stand without risk of serious injury when supported by the present invention harness and novel shock absorbing brake means. Also, in the event of a crash and acceleration forces, the expected acceleration is negative, and forceapplied to the body of the harness wearer and seat occupant will be in a forward direction.

Any means suitable to apply the brake shoes, such as air. pressure or springs may be substituted for explosive gases. in the auxiliary shock absorber means for the. harness belt 13, shown in Figure 3, there is shown a brake shoe applying spring 50 in a housing 51 supported by the bracket 27. Bracket 27 also connects to the end of spring 24 as before explained. The lower part of the housing is formed with diametrically opposite elongated slots 52 and 53 extending from the bottom 54.

Resting on the bottom 54 is a brake shoe 55 over which stretches a medial part of a ribbon 56 tapered in cross section. One end of the ribbon 56 is coupled to the converging ends of a belt or waist portion 13 by a flexible strand 57. This strand or any of the several harness straps maybe made of undrawn or unoriented synthetic plastic fibers. Above the upper surface of the ribbon 56 is an upper brake shoe 58, which is held pressed into contact with the ribbon by a plate 59 formed with side lugs 60 and 61. These lugs ride in the guide slots 52 and 53 and by virtue of the spring 50 in the housing 51 are held constantly engaged with the flat sides of the ribbon 56.

The plate 59 may include a raised portion 62 which serves to retain the spring 50 centered on the plate.

One of the important features of the present invention resides in the tapered ribbons 21 and 56. Such taper provides for a progressively greater and greater braking ac tion as maximum tolerable G is approached. At the first pull on the tape the thin part of the tape offers no braking action and thus serves as a temporary brake delay thereby aiding in reduction of initial shock.

Operation The operation of the present invention is probably.

clear from the foregoing description. Briefly summarizing and assuming the airplane crashes the resultant forward force will actuate the accelerometer if the force exceeds, for example, 2 G thereby releasing the weight 32. When the weight hits the head of the firing pin 31 and explodes the cartridge 29, the explosive gases flow into and expand within the chamber 17. Such expansion forces the piston 17a forwardagainst the'brake shoe 22 and causes engagement of the shoes 22 and 23. with the thin end of the tapered. tape or ribbon 21.

Now the occupant of the seat S is progressively restrained against moving forward beyond maximum tolerable G. As maximum tolerable G is approached the pull on the shoulder straps 12 is suflicient to proportionally pull on the tape 21 and progressively retard the shock as the forward acceleration force is increased.

A similar action takes place from any pull forward imparted from the belt or waist strap 13 to the tape 56 between brake shoes 55 and 58.

Thus there is provided an accelerometer operated shockabsorbing means for vehicle seats adapted to progressively absorb sudden shocks imparted to the occupant ofthe seat and maintain such acceleration forces below the threshold of maximum tolerable G resulting from crashes or the like. The shock absorbing means is also so constructed as to be readily installed and may be manufactured under mass production as individual units.

While the present invention has been described in detail for substantially only one embodiment, it is to be expressly understood that'various changes and modifications,

which will now probably occur to those skilled in theseat comprising brake means including a housing formed with oppositely positioned slots, a bracket fixed" to the vehicle supporting the housing, a brake shoe mounted in the housing on each side of the slots, an elongated tapered flexible tape extending through the housing and said slots andbetween the brake shoes, said tape having one endthereof yieldably connected to said harness and the other end thereof resiliently connected to a fixed part of the vehicle, said tape having opposed brake shoe engageable sides which convergefrom said resiliently connected end thereof to said harness connected end thereof, a cartridge in the upper part of the housing, a pin for exploding said cartridge, a crash released weight for driving said pin into the cartridge, a piston in the housing above the upper brake shoe movable by theexpansion of the gases in the housing, whereby the brake shoesare moved into engagement'with the tapered faces of the tape and progressively restrain the passage of said tapered faces of the tape between them to provide a predetermined slipping load to equal the highest load that the human body can stand without serious injury.

2-. Shock absorbing means for vehicle carried seats comprising an elongated flexible member movable in response to forward forces imparted from the shoulder straps and waist straps of an occupied safety harness to which one end of said member isconnected, said flexible member having its opposite end resiliently and yieldably connected to a fixed element of the vehicle, brake shoes mounted in a brake housing fixed with respect tosaid flexible member acceleration forces for releasing said fluid pressure to said piston to actuate the brake shoes into. slipping engagement with said flexible member. under predetermined load,

said member absorbing energy by said slipping action, to.

thereby restrain: the forwardmovement. of the wearer of the harness and occupant of the associated seat below the threshold of a maximum tolerable acceleration.

3. Shock absorbing means for vehicle carried seats comprising a pair of elongated metal ribbons movable in response to forward forces imparted from the harness worn by an occupant of the vehicle seat, each of said ribbons being yieldably connected at one end thereof to said harness and at least one of said ribbons having its opposite end resiliently connected to a fixed part of the vehicle, a brake shoe disposed at each of the opposite sides of each ribbon frictionally engageable therewith for resisting pull on said harness with a resulting slipping movement of the ribbon, the brake shoes cooperating with one of said ribbons being disposed within a cylinder fixed to said seat, a cartridge chamber in communication with said cylinder adapted to support a gas forming cartridge for gas operation of said last brake shoes, inertia means supported adjacent said cartridge chamber, and crash releasable means for retaining said inertia means in an inactive position until a crash occurs.

4. The arrangement as described in claim 3, wherein each of said ribbons is tapered with the brake shoe engageable sides thereof converging toward said yieldable connection thereof with said harness.

References Cited in the file of this patent UNITED STATES PATENTS 

